Air pump



Feb, l1, 1941. J.F. WALLACE AIR PUMP Original Filed March 225, 1937 mmh.

ATTOR N EY Patented Feb. 11, 1941 UNITED STATES PATENT OFFICE AIR PUMPSubstitute for abandoned application Serial No. 132,554, March 23, 1937.This application May 10, 1940, Serial No. 334,403

5 Claims.

This invention relates broadly to an improvement in air pumps, but moreparticularly to power actuated pumps designed to discharge air underhigh pressure.

This application is a substitute for my prior application Serial No.132,554, filed March 23, 1937, and since abandoned.

One object of this invention is to produce an improved high pressure airpump of simple construction which is strong, durable and efiicient,

Another object of this invention is to produce a portable air pump,actuated by compressed air and adapted to deliver air under highpressure.

Another object of this invention is to provide a new and improvedcooling system for a high pressure portable pump of the reciprocatorypiston type.

A further object of this invention is to provide a device of thischaracter which .may readily be disabled for cleaning, lubrication orinspection of parts.

Other objects and advantages more or less ancillary to the foregoingreside in the specific construction and aggroupment of the elementspeculiar to this structure, as will become apparent from a more completeexamination of this specification.

In the drawing which illustrates a preferred form of the invention:

Fig. 1 is a longitudinal sectional view of the pump illustrating themovable parts in one position.

Fig. 2 is a view similar to Fig. l illustrating the movable parts inanother position.

Referring to the drawing in which like symbols designate correspondingparts throughout the several views, I represents a center head having askirt I I within which there is threaded in uid tight engagementtherewith one end of a cylindrical casing hereinafter denoted as motorcylinder I2. The other end of this housing is also closed by a cover I 3screwed thereon in fluid tight engagement therewith. I

The center head I0 is also formed with a cylindrical stem I4 havingscrewed therein in fluid tight engagement therewith one end of a barrelor pump cylinder I5 which extends therefrom coaxially with the housingI2, and has its other end carrying a cap I6 mounted thereon in screwtight engagement therewith.

Extending through the center head I 0, there is a bore I 1disposedcoaxially with the motor cylinder l2 and the pump cylinder I5,and having a sleeve valve I8 slidable therein between the adjacent endsof the pump cylinder I5 and of a bushing I9 secured within the bore I1.This valve is formed. with an external annular groove 20 capable ofcommunication with two smaller internal annular grooves 2l and 22 formedwithin the bore I1, the groove 2| having one end of an inlet port 23opening therein while the other end carries a bushing 24 adapted toreceive one end of a fluid conveying conduit (not shown). Leading fromthe groove 22, there is a port 25 terminated by a pipe connection 26mounted therein and comprisin'g an elbow 2l having one end of a smallpipe or conduit 28 secured therein by a coupling nut 29. The pipe 28extends to the outer end of the cylinder I2 where it is connected to thecover I3 by a connection 30, which connection is a replica of theconnection 26. From the connection 30, the fluid may be admitted intothe motor cylinder I2 through a port 3| provided within the cover I3.

Leading from the inlet port 23, there is a port 32 threaded to receive apipe connection 33 by which one end of a pipe 34 is connected to theport 32. The pipe 34 extends toward the outer end of the cylinder I5 andhas its other end secured to the cap I6 by a pipe connection including amember 35 threaded to receive a coupling nut 36 and having a port 31therethrough normally closed by a spring pressed check valve 38. Fromthe port 31, the fluid may be admitted into the outer end of the pumpcylinder I5 through a port 39 formed within the cap I6. Also secured tothe cap I6, there is a conduit connection 40 having a port 4I extendingtherethrough and opening into the outer end of the cylinder I5, whichport is normally closed by a spring pressed check valve 42.

Surrounding the cylinder I5, there is a shroud 43 extending from thecenter head I0 to the cap I6 to form a cooling chamber 44 around thecylinder I5, and within which is `contained the pipe 34. This coolingchamber is in constant communication with the atmosphere through anexhaust port 45 extending through the cap I6, and with the inner end ofthe motor housing I2 through a passage 46 extending through the centerhead I0.

The valve I8 is also provided with two external annular grooves 41 and48 adapted to receive a spring pressed ball or detent 49 for locking thevalve in two different positions.

Extending through the valve I8, there is a bore 50 having a piston rod5I slidable therethrough and having one end projectinginto the cylinderI5 to receive a piston formed of a flexible packing 52 secured theretoby a nut 53. A compression spring 54 is loosely mounted on the pistonrod 5| between the piston 52 and the valve I8, the purpose of which willbe explained later,

The other end of the piston rod 5I extends into the motor cylinder I 2to receive a piston formed of a flexible packing 55 clamped between twoplates 56 and 51, the plate 56 being screwed o n the rod 5I, while theplate 51 is secured in position by a nut 58. A compression spring 59 isalso loosely mounted on the piston rcd between the valve I8 and thepisto-n 55.

The valve bore 50 through which the' piston rod is free to slide, is ofa diameter materially larger than that of the rod, thereby affording anannular passage between the lower end of the barrel I5 and the upper endof the motor cylinder I2.

In the operation of the device, compressed air from its source of supplyis admitted into the inlet port 23 through the connection 24. When thepistons and the valve are positioned as shown in Fig. 1, the compressedfluid from the port 23 will flow into the port 25 via the grooves 2|, 20and 22, from where it will be admitted into the outer end of the motorcylinder I2 through the pipe 28 and the port 3l. Simultaneously thepressure fluid from the port 23 will flow into th-e pump cylinder I5 viathe port 32, the pipe 34 and the ports 3'I and 39. During this inletflow of the pressure fluid into the cylinder I5, the check valve 31 isshifted in open position relative to the port 31 due to the inlet flowof the pressure fluid, while the check valve 42 remains temporarily in aclosed position relative to the port 4I due to the compression springacting on the valve 42, which compression is calculated to withstand thepressure of the fluid admitted into the pump cylinder I5. The pressurefluid acting on the piston 55 will drive the latter toward the inner endof the housing I2, thereby effecting the corresponding movement of thepiston 52 into the pump cylinder I5.

As shown, the diameter of the motor piston 55 is materially larger thanthat of the pump piston 52, in fact the cross sectional area of theformer is calculated to be about ten times larger than that of thelatter, thus providing a ten to one compression ratio between the twopistons. The compressed air admitted into the inlet port 23 anddistributed therefrom into the motor cylinder I2 and the pump cylinderI5, is usually obtained from small portable compressors delivering airunder an average 'pressure of 100 pounds per square inch. Thiscompressed air acting on the motor piston 55 will drive the pump piston52 to force the air therefrom under higher pressure through theconnection 40 by opening the check valve 42, while the check valve 31 isnow closed by air under higher pressure flowing from the cylinder I5.Should the element 48 be connected to a tank or the like within whichhighly compressed air is needed, it will be understood that due to thedifference between the cross sectional areas of the two pistons, the airadmitted into the tank may reach a pressure about ten times higher thanthat of the air admitted into the inlet port 23.

Toward the end of the working stroke of the piston 55, the compressionspring 59 will engage the valve I8 to shift it into the position shownin Fig. 2, thereby preventing the flow of the pressure fluid from theinlet port 23 into the motor cylinder I2. During this position of thevalve I8, the pressure fluid is still admitted from the inlet port 23into the cylinder I5 la the pipe 34, thereby acting on the piston 52 fordriving it, together with the piston 55, into the position shown inFig. 1. Simultaneously, the pressure fluid previously admitted into themotor cylinder I2, is exhausting from the outer end into the inner endthereof via the port 3|, the pipe 28, the port 25 and the bore I1. Fromthe inner end of the cylinder I2, the exhausting fluid will flow intothe cooling chamber 44 via the port 36, where it will flow around thepump cylinder I5 and finally escape to the atmosphere through the port45. The flow of the exhausting uid through the chamber 44 and around thecylinder I5 will act as a cooling medium for the cylinder, therebypreventing the latter from reaching an excessive temperature which wouldotherwise result from the high compression taking place therein.

During the return movement of the pistons above referred to, air underatmospheric pressure which may be contained within the cylinder I5 underthe piston 52, is also free to exhaust therefrom through the valve bore50 into the inner end of the motor cylinder I2, from where it willescape to the atmosphere through the port 26, the chamber 44 and theexhaust port 45.

Toward the end of the return stroke of the pistons, the compressionspring 54 engaging the valve I8, will be compressed by the piston 52 tocause the shifting of the valve from the position shown in Fig. 2 to theposition shown in Fig. 1. In this last position of the Valve, thecompressed air will again be admitted into the motor cylinder I2 in themanner previously described to cause the compression of the aircontinuously admitted into the cylinder I5. During the working stroke ofthe piston 56, the air under atmospheric pressure contained within themotor cylinder I0 between the piston 55 and the center head I0 is freeto exhaust therefrom through the port 46,`,the cooling chamber 44 andthe exhaust port 45.

Although the foregoing description is necessarily of a detailedcharacter, in order to completely set forth the invention, it is tobe'understood that the specific terminology is not intended to berestrictive or confining and it is to be further understood that variousrearrangements of parts and modificationv of structural detail may beresorted to without departing from the scope or spirit of the inventionas herein claimed.

I claim:

1. In a device of the character described, the combination of a motorand pump each including a cylinder having a piston slidable therein,said cylinders being mounted coaxially with a center head therebetween,a bore extending through said center head, a rod connecting said pistonsslidable through said bore, means for admitting motive uid on one sideof the motor piston for effecting the working stroke of said pistons andonone side of said pump piston for effecting the return stroke of saidpistons, and means including said bore affording communication of saidone side of the motor piston and the other side of said pump piston withthe atmosphere during the return stroke aforesaid.

2. In a device of the character described, the combination of a motorand a pump each including a cylinder having a piston slidable therein,said cylinders being mounted coaxially with a center head therebetween,a bore extending through said center head having a valve slidabletherein, a bore through said valve, a rod connecting said pistonsslidable through said valve bore, passageways for admitting motive fluidon 75 one side of the motor piston for effecting the working stroke ofthe pistons and on one side of the pump piston for effecting the returnstroke o'f the pistons, said valve being actuated by said pistons forcontrolling one of said passageways, and means for venting the otherside of said pump piston during the return stroke thereof including saidvalve and said center head bore and for simultaneously venting said oneside of said motor piston including said center head bore.

3. In a device of the character described, a motor housing and a pumphousing mounted coaxially, a center head between said housings having abore extending therethrough, a slidable piston within each housinginterconnected by a rod extending through said bore, a valve slidablewithin said bore, a passageway for each of said housings admittingpiston actuating uid therein contacting with and acting on said piston,said Valve being actuated by said pistons for controlling one of saidpassageways, means subjected to pressure conditions within said pumphousing for controlling the other of said passageways, and meansincluding said bore for exhausting motive fluid from at least one ofsaid housings during a predetermined position of said valve.

4. In a device of the character described, a motor cylinder and a pumpcylinder mounted coaxially. a v center head between said cylindershaving a bore extending therethrough, a slidable piston within eachcylinder interconnected by a rod extending through said bore, a valveslidable within said bore, a duality of passageways for alternativelyadmitting motive uid into the outer ends of said cylinders for effectingthe working and return strokes of said pistons, said valve beingactuated by said pistons for controlling one of said passageways, meanssubjected to pressure conditions Within said pump cylinder forcontrolling the other of said passageways, and means including said boreand valve for constantly venting the inner ends of said cylinders.

5. In'a device of the character described, a motor cylinder and a pumpcylinder mounted coaxially, a center head between said cylinders, aslidable piston within each cylinder interconnected by a rod slidablethrough said center head, a duality of passageways for alternativelyadmitting motive uid into the outer ends of said cylinders for effectingthe working and return strokes of said pistons, an exhaust port throughsaid center head for constantly venting the inner ends of saidcylinders, and means including one of said passageways and said exhaustport for venting the outer end of said motor cylinder during the returnstrokes of said pistons.

JOHN F. WALLACE.

